The overall goal of this research is the design, development and in vivo testing of an engineering type I collagen based ligament template to support the regeneration of the anterior cruciate ligament (ACL) of the knee joint. In the Phase I period, we have accomplished most of the objectives. Specifically, we have designed and developed an extrusion apparatus for the extrusion of collagen filaments; we have tested the extrusion variables for the production of uniform and reproducible filaments: we have studied various crosslinking agents for the toxicity and cytocompatiblity of the various crosslinked materials and defined the most suitable crosslinking agent for crosslinking the filaments; we have defined the overall mechanical strength requirement of the ligament template for canine implantation; and we have implanted the prototypes into eight canin knee joints for ACL reconstruction. During the Phase II, we will continue to improve the design and fabrication procedures and evaluate the safety and efficacy parameters of the collagen ligament template. We will conduct a large scale animal study on the best-defined prototype to evaluate the longer term effects of the implant through the resorption-regeneration-remodeling-maturation phase of the implant The successful results of this Phase II research will likely lead to a clinica trial and commercialization of the product. Nearly 110,000 ACL injuries per year in the U.S. alone and greater than one-third of the injured patients require repair and reconstruction. AC: reconstruction is generally performed by autografting (bone-patellar tendon-bone). In addition to the creation of a second injury site, autograftin often results in pain and strength loss in the quadriceps and requires extende rehabilitation times. There is no ideal method that ensures the restoration of a normal functioning knee. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE